Milford Sound Weather: Climate, Rain and the Best Time to Visit

Monthly Climate Table

The table lists the mean daily maximum, the mean daily minimum, the mean monthly rainfall and the mean number of rain days for every month, taken from the 1991-2020 climate normals recorded at Milford Sound Airport. For context, the annual mean daily maximum is 14.9 C, the annual mean daily minimum is 6.4 C and the mean temperature is 10.6 C. The records since 1934 stand at 29.4 C in February and -6.1 C in July. Mean relative humidity runs from 88.9% in December to 95.2% in June, and the average relative humidity for the year is 92.8%.

What the Table Means for a Cruise

Read the table one way and the answer is always the same. Every month brings at least 440 mm of rain and at least 12.8 rain days, so any cruise day carries a decent chance of shower. February is the statistical best bet, with the warmest high at 20.0 C and the fewest rain days at 12.8. September and October are the wettest by count of rain days at 17.6 each, even though their rain totals sit near the middle of the range.

Read it a second way and the numbers stop mattering much. Rainfall at the fiord can reach 250 mm in 24 hours, and that kind of downpour makes dozens of temporary waterfalls, some falling a thousand metres down rock. The same rain can send whole sections of rainforest sliding off the sheer cliffs as tree avalanches. The weather you get on the day matters more than the month you booked, which is why checking the forecast the evening before is worth more than picking a statistically dry month.

One more useful contrast. Te Anau, the usual overnight base, gets 1,202.5 mm of rain a year against more than 6,000 mm at Milford Sound. A blue morning in Te Anau tells you almost nothing about conditions at the coast, 120 km away through the mountains.

How Much Rain Actually Falls

The sources disagree on the exact figure, which is itself useful to know. DOC says Milford Sound gets up to 7 m of rain per year. Wikipedia gives 6,412 mm annually, while the twelve monthly normals on the same table add up to 6,545.1 mm. Southern Discoveries puts it at around 7.5 m a year. Whatever number you take, the scale is the same: several metres of water arrive over the fiord every year, several times what falls on Te Anau (1,202.5 mm a year).

Rain days tell the same story. Wikipedia counts 184.8 rainy days a year, Southern Discoveries says 182 on one page and about 200 on another. On roughly half the days of the year, some rain falls.

Why Rainy Days Make Better Waterfalls

Milford Sound has only two permanent waterfalls, Stirling Falls and Bowen Falls. Bowen Falls, named Hineteawa in Maori, drop about 160 metres and are fed by the 9 km Bowen River. Stirling Falls sits at 151 metres by Wikipedia's measure, though Southern Discoveries lists it as 155 metre high, and has existed for 15,000 years. Everything else on the cliff faces is rain-fed.

When it rains, hundreds of temporary cascades form along the mountainsides. They are fed by rain-soaked moss and last a few days after the rain stops, so a cruise a day after a storm still finds them running. Semi-permanent falls such as Fairy Falls and Palisade Falls can last up to two weeks without rain, and Fairy Falls rarely dries up completely even in summer. RealNZ puts it plainly: many say you have not seen Fiordland unless you have seen it in the rain.

The practical consequence is that you can cruise Milford Sound 365 days a year. Rain does not close the fiord, and a glass-roof catamaran cruise with indoor seating and outdoor decks works in both states of the sky. DOC's advice for the fiord is simply that every visitor should have a good raincoat.

Summer, December to February

RealNZ puts summer at 18-25 C and Glenorchy Air calls December to February the busiest months, with long daylight, warmer temperatures and frequent dolphin and fur seal sightings. In summer it does not get dark until after 9:00pm, which stretches what you can fit into a day. January is the busiest month at the fiord, and RealNZ says summer needs booking well ahead. Wikipedia notes that roads and facilities are congested in the main season because tour operators from Queenstown leave very early, so most visitors reach Milford Sound within a few hours of midday.

RealNZ also says morning departures are generally quieter with calmer water before the afternoon winds, advice that matters most in summer when every departure fills.

Autumn, March to May

RealNZ puts autumn at 12-20 C. Glenorchy Air says autumn brings dramatic waterfalls, softer light and noticeably smaller crowds than summer. The monthly table shows the temperature drop: March still averages an 18.5 C high, while May drops to 12.5 C with 645.1 mm of rain.

Winter, June to August

Winter runs June to August at 5-10 C by RealNZ's reckoning, and Glenorchy Air calls it the quietest season, with snow-capped peaks and crisp skies. Snow settles on Mitre Peak from June onward. Intrepid says winter brings maximum solitude and spectacular waterfalls from torrential downpours but needs thermal clothing. July is the coldest month in the table, a 9.2 C high and a 1.6 C low, and the record low of -6.1 C was set in July.

The catch sits on the road. Wikipedia says the Milford winter road is very prone to avalanches and closures during the winter half of the year. Between May and November, when required, all vehicles on the Milford Road must carry or fit snow chains, and Milford Lodge phrases the rule as June through November, conditional on road status. Chains can be hired at any Te Anau petrol station. Marian Corner avalanche gates close whenever there is avalanche danger, and the road stays shut until explosives clear the snow.

Against that, July to November is the best window for penguins. See the next block, or the rain and wildlife section of the homepage for the wider animal picture.

Spring, September to November, and Penguin Season

RealNZ puts spring at 10-18 C and picks November as a strong month, with reliable weather, fewer visitors than peak summer and active wildlife. Glenorchy Air says spring has waterfalls at their fullest, seal pups on the coast and vivid green rainforest. Daylight saving begins in late September, which adds evening light.

The wildlife headline is penguins. The best time to see Fiordland crested penguins, tawaki, is the July to November breeding season, and Milford Sound is one of the places to spot them, so winter and early spring are the prime viewing months. The tawaki population is between 2,500 and 3,000 breeding pairs, each bird about 55 cm long and averaging 3.5 kg. They can sometimes also be seen during moulting from mid-January to early March. RealNZ adds that seal pups and penguin chicks appear in spring and lupins bloom along the Milford Road.

If none of these suits, remember that Fiordland weather does not follow the calendar closely, so clear visibility is possible in any month. The pick for a single recommendation is November, but any month works with the right expectations. For seeing the fiord at its quietest, an overnight cruise lets you stay after the day buses leave, and RealNZ says it gives a dawn stillness and light quality that daytime cruises cannot.

Flights and Weather

Charter flights into Milford Sound Airport run daily weather permitting. The airport has a single 782 m asphalt runway at the head of the fiord, 3 m above sea level, and Queenstown Airport says the flight from Queenstown typically takes 30-40 minutes one way. Flights run weather permitting, so low cloud or strong wind can cancel them.

The operators build for this. Milford Sound Scenic Flights checks the weather 1.5 hours before departure. RealNZ says when a flight is cancelled the guest returns by coach and the flight component is refunded, and Glenorchy Air makes the same promise: if conditions are unsafe, passengers return to Queenstown by coach. So a weather cancellation costs you the flight leg, and the operator's terms decide the rest. Which fly-cruise packages include that guarantee is laid out on the Milford Sound scenic flight page, and if you want the flight leg as the point of the day, the Fly-Cruise-Fly from Queenstown runs 5 hours door to door with a 2-hour cruise.

Road Closures and Avalanches

SH94, the Milford Road, stays open year-round but carries avalanche control closures between June and October, per RealNZ. In winter the road is closed if there is avalanche danger until explosives clear the snow, and the road is closed an average of 8 days a year, mainly in winter. The Marian Corner gates and the 'Avalanche Area No Stopping' signs must be obeyed whenever they are up.

There is no mobile phone coverage along the Milford Road, so check road conditions on 0800 4 HIGHWAYS (0800 444 449) before you leave Te Anau, and again at the last point of coverage. Drivers planning the trip themselves should read the Milford Road guide for the stop-by-stop detail, or leave the car and take a coach day trip.